Preface:
At the time of this DIY I am only familiar with three different 993 aluminum gauge face options in the aftermarket world. 

Option #1 Factory option - The factory option is done by applying a silver vinyl sticker over the standard black face plates, the flaw with the paper option is that the vinyl sticker will bubble up overtime and cause an ugly appearance.  During my research I was also told that this particular option was actually performed by TechArt in Germany for Porsche. 

Option #2 TechArt option - Most similar with the factory option, but does not have the bubble up problem.  ( I am guessing TechArt must have kept one in their sleeves for themselves)  Around $450 for the faces. 

Option #3 NR Automobile option - NR Automobile is a 3rd party aftermarket accessories manufacturer who came out with their own solution for the aluminum gauge faces.  The main difference with the NR gauge faces is that the gauge faces do not have the individual cut outs for the warning lights.  And that the NR gauge face option allow less light to shine through the gauge faces at night. The cost of the NR gauge faces are around $180-$240 for the set.  This is the option I choose to use in this DIY project.

I purchased the NR Automobile aluminum gauge faces from "By Design" in California, owner Michael is offering a discounted price of $180 per set to any Rennlist member who is interested in purchasing the gauge faces.  Their phone number is 888-993-2911. 

I choose to do this DIY upgrade to my 993 because I had to opportunity to acquired an used set of 993 factory aluminum gauges which have bubbles on few of the gauges.  I was not able to squeeze the bubble out from the vinyl stickers so I thought to just replace them with a new set of gauge faces.  One of the interesting finding during the DIY was that I noticed that on the factory aluminum gauges the bezel ring have a silver/chrome linings on the inside instead of black like the standard gauges.

Prior to installing the new gauge faces I do recommend the following two modifications to be performed in order for the new gauge faces to have the similar night time illumination level as the original factory gauge faces.

When ordering the gauge faces you will need to specify if your car is a Tiptronic or a manual transmission, or if it has the OBC option.  The set I received in the above picture is for a manual transmission 993.

Removal of the gauges from the dash 
To remove the gauge from the dash warp a shop towel around the tip of a flat screw driver and pry the speedometer gauge from the right side out first.  Through my experience I found this is the easiest gauge to remove especially when using the clock gauge as leverage.  You can place another towel in front of the clock gauge to protect it from being scratched.  Once the speedometer is removed and unplugged you will be able to easily pop the clock gauge out from behind, and the rest of the gauges.  The tachometer would be the most difficult to remove since it will hit the steering column as it comes out.  As a reference I was able to take out and install the tachometer without removing the steering column cover.  As suggested by Tim Ashfield steering column cover removal is required for 993 owners with OBC option. 

Bezel ring removal
Once the gauges are remove place them on a padded work surface, now it is time to remove the bezel ring in order to replace the gauge faces.  I used various different flat screw drivers and pick tools to roll back the bezel lip.  I found that you don't have to roll back all the lip area to be able to remove the bezel ring from the gauges.  The instructions that came with the kit mentioned to use a soup can to roll the lips back during installation, I just rolled them back using the flat screw driver since I didn't have to pry all the lip edge out. 
 

Needle removal and calibration
In order to replace the gauge faces you will also need to remove the gauge needles, to remove the needles use your finger to gently turn the needle counter-clockwise under it reaches the end and continue to turn it with your finger in a unscrewing motion the needled should pull right out.  Most of the needles just pulls right out, the only gauge I really had to turn the needle counter clockwise was the speedometer needle.  To calibrate the needle after installation you will need to use your finger to turn the needle to the stop point and force the needles to pass the stop point and vice versa for the opposite direction.

On the clock gauge face there are two specific notches that needs to be made to the NR gauge face (marked on the NR gauge where the notch needs to be)  prior to installation as the gauge face will not fit if the notches are not made.  The below picture show where the notches needs to be made according to the factory face. 

There are couple of things to watch out for when replacing the speedometer gauge face. 

Once the bezel ring is removed you will have remove the round sleeve cover on the trip reset pole before you can remove the glass, most likely you will end up yanking the whole thing off the reset mechanism where you will have to go back and snap it back in with the help of a tweezer.  A little trick in preventing that from happening is to put pressure on the trip reset shaft which twisting and pulling the sleeve cover.  If you are careful you should be able to remove the sleeve cover without pulling the whole shaft off the reset mechanism.

If you did accidentally pulled it off, you will need to snap back the reset shaft  once the gauge face is removed. 

Prior to removing the gauge face I recommend popping out the miles brackets window first. 

The speedometer needle is the only needle that I found can not be pull off like the others, it must be turned counterclockwise and pulled at the same time.

Additional note:  Regarding odometer tamper proof.  For those worry about the speedometer showing signs of tampering from replacing the gauge faces.  In order to really tamper with the mileage reading you will have to take apart the entire speedometer unit which means by breaking the seals on the screw behind the speedometer to gain access to the mile wheel. 

Below are some difference in appearance when viewed at night, as I have mentioned in the beginning of this DIY that the NR Automobile gauges do not allow too much light to shine through the silver gauge faces and the needles are very difficult ot see at night.  (I apologize for the fuzzy pictures, I had a difficult time keeping my hands still while taking these pictures with extended time exposure) 

Note: In effort to save cost with this upgrade I didn't choose to go with the more expense TechArt gauge face option, so I am stuck with the night time illumination problem with the NR Automotive gauge faces.  The below DIY modification is an effort in trying to enhance the brightness of night time illumination.

There are two level of illumination source behind each of gauge, one is for the back ground illumination which is provided by a 0.9 watt 12 volt DC bulb, the other is for the warning lights which is provided by a 1.5 watt 12 volt DC bulb.  The first step I took in effort to brighten the background illumination was to switch out all the 0.9 watt bulbs to the 1.5 watt bulbs, hoping that it would be enough to at least light up the needle a little more.

Before	After

Plan B is to add more light source INSIDE of the gauge itself, I decided only to add additional light sources into the tachometer, and the speedometer since they are the two gauges that I am most concern about.
 
 

The factory only provided TWO illumination bulbs inside the tach for back ground illumination, which explains why it is so dim with the aluminum gauge face installed. 

My plan was to add 4 more bulbs in there, 3 for the tach number read out, and 1 for the needle.  To do this the inner part of the tach will need to be remove from the housing.  First remove the three screws on the back of the tach.

Once the screws are removed the inner part of the tach can be removed.  Remove the two screw that secures the clear plastic light inducer from the motor housing.

Pry open the two plastic clips on the back of the inner tach in order to move the motor housing away from the PCB to reveal the solder side of the plug pins.  The purpose is to expose the solder side of the plug pins so that you can solder two wires which will be used for the additional light bulbs that will be installed.

Cut open the wire around the tach where the additional light would be installed and solder the light bulb contacts directly to the exposed wire, hot glue the additional bulbs directly on to the PCB.   Below is a picture of the additional bulbs that was added and their locations. 

Before	After

Adding more lights into the speedometer was a lot more difficult since I wanted to protect the integrity of the mileage reading so I didn't want to remove the tamper proof screws in the back of the speedometer. 

First solder two wires directly on to harness plug pin on the back of the speedometer.

Make modification on the factory light bulb holder so that there is an opening for the wire to go through.  And run the wire from where the soldering was done to this hole opening.

Strip the wire where the bulbs will be soldered onto and place the lights around the gauge.  I only added two additional light source mainly to provide extra light in the 40-90 mph range.  The light were not fixed to the PCB of the speedometer, because I wanted them to be as close to the gauge face as possible.  The wires I used were stiff enough to hold them in position. 

Before	After

As you can see from the above pictures something still doesn't look kosher with the gauges at night.  Hopefully after you've stared at the above pictures long enough you will notice that  the needle don't light up!  The part 1 of the modification process fixed the back ground illumination issue, part 2 of the modification process will address the illumination of the needles.

After doing some comparison of the original factory faces to the new aluminum gauge faces I noticed that the gauge needles were illuminated by lights shinning through the opening around the axis of the needle on the factory black gauges faces.  The lack of needle illumination with the NR aluminum gauges  were caused by the lack of this opening.    When I looked carefully on the back of the NR aluminum gauge faces I noticed that there is a round outline around the needle opening where there shouldn't have been paint there.  I assume they screw up during the printing process and painted over the area that was supposed to be left clear.   Below picture shows the area I am referring to.

So my next step was to scrap off the painted area around the hole opening with a razor blade by following the faint outline. 

Note: The only gauge that did not require this modification process was the clock gauge
 
 

Before	After  (the difference with the needle)

Before	After

Before	After